Windows 10 S will only allow you to run apps from the Microsoft Store, which means you can't run iTunes or Chrome, unless you pay US$49 to upgrade it into an actual Windows.

I'm fairly sure RMS warned us around 20 years ago that this kind of stuff was coming, and people laughed and said 'that's paranoia, they'll never lock the desktop down that far'.

https://www.theguardian.com/technology/2017/may/03/windows-10-s-microsoft-faster-pc-comparison